Refactor|libdeng2|Script: Added DeleteStatement

Deleting is now a proper statement, which matches the semantics of
the script language.

This forces records to observe their members for deletion.

doomsday/libdeng2/include/de/DeleteStatement

@@ -0,0 +1 @@
+#include "scriptsys/deletestatement.h"

doomsday/libdeng2/include/de/data/record.h

@@ -46,7 +46,8 @@ namespace de
      *
      * @ingroup data
      */
-    class DENG2_PUBLIC Record : public ISerializable, public LogEntry::Arg::Base
+    class DENG2_PUBLIC Record : public ISerializable, public LogEntry::Arg::Base,
+                                DENG2_OBSERVES(Variable, Deletion)
     {
     public:
         /// Unknown variable name was given. @ingroup errors
@@ -298,7 +299,10 @@ namespace de
         // Implements LogEntry::Arg::Base.
         LogEntry::Arg::Type logEntryArgType() const { return LogEntry::Arg::STRING; }
         String asText() const { return asText("", 0); }
-
+
+        // Observes Variable deletion.
+        void variableBeingDeleted(Variable &variable);
+
     private:
         struct Instance;
         Instance * d;

doomsday/libdeng2/include/de/data/recordvalue.h

@@ -98,6 +98,7 @@ class DENG2_PUBLIC RecordValue : public Value, DENG2_OBSERVES(Record, Deletion)
     Value *duplicate() const;
     Text asText() const;
     dsize size() const;
+    void setElement(Value const &index, Value *elementValue);
     Value *duplicateElement(Value const &value) const;
     bool contains(Value const &value) const;
     bool isTrue() const;
@@ -113,7 +114,7 @@ class DENG2_PUBLIC RecordValue : public Value, DENG2_OBSERVES(Record, Deletion)
 public:
     Record *_record;
     OwnershipFlags _ownership;
-    OwnershipFlags _oldOwnership;
+    OwnershipFlags _oldOwnership; // prior to serialization
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(RecordValue::OwnershipFlags)

doomsday/libdeng2/include/de/scriptsys/deletestatement.h

@@ -0,0 +1,66 @@
+/*
+ * The Doomsday Engine Project -- libdeng2
+ *
+ * Copyright (c) 2012-2013 Jaakko Keränen <jaakko.keranen@iki.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBDENG2_DELETESTATEMENT_H
+#define LIBDENG2_DELETESTATEMENT_H
+
+#include "../libdeng2.h"
+#include "../Statement"
+#include "../ArrayExpression"
+#include <string>
+#include <vector>
+
+namespace de
+{
+    /**
+     * Deletes variables.
+     *
+     * @ingroup script
+     */
+    class DeleteStatement : public Statement
+    {
+    public:
+        /// Trying to delete something other than a reference (RefValue). @ingroup errors
+        DENG2_ERROR(LeftValueError);
+
+    public:
+        DeleteStatement();
+
+        /**
+         * Constructor.
+         *
+         * @param targets  Expression that resolves to a reference (array of RefValues).
+         *                 Statement gets ownership.
+         */
+        DeleteStatement(ArrayExpression *targets);
+
+        ~DeleteStatement();
+
+        void execute(Context &context) const;
+
+        // Implements ISerializable.
+        void operator >> (Writer &to) const;
+        void operator << (Reader &from);
+
+    private:
+        ArrayExpression *_targets;
+    };
+}
+
+#endif /* LIBDENG2_DELETESTATEMENT_H */

doomsday/libdeng2/include/de/scriptsys/expression.h

@@ -62,7 +62,7 @@ namespace de
             NewSubrecord = 0x8,
 
             /// Identifier must exist and will be deleted.
-            Delete = 0x10,
+            //Delete = 0x10,
 
             /// Imports an external namespace into the local namespace (as a reference).
             Import = 0x20,

doomsday/libdeng2/include/de/scriptsys/parser.h

@@ -39,6 +39,7 @@ namespace de
     class WhileStatement;
     class ForStatement;
     class AssignStatement;
+    class DeleteStatement;
     class FunctionStatement;
     class ArrayExpression;
     class DictionaryExpression;
@@ -101,7 +102,7 @@ namespace de
 
         ExpressionStatement *parseDeclarationStatement();
 
-        ExpressionStatement *parseDeleteStatement();
+        DeleteStatement *parseDeleteStatement();
 
         FunctionStatement *parseFunctionStatement();
 

doomsday/libdeng2/include/de/scriptsys/statement.h

@@ -71,7 +71,8 @@ namespace de
             IF,
             PRINT,
             TRY,
-            WHILE
+            WHILE,
+            DELETE
         };
 
     private:

doomsday/libdeng2/scriptsys.pri

@@ -6,6 +6,7 @@ HEADERS += \
     include/de/Compound \
     include/de/ConstantExpression \
     include/de/Context \
+    include/de/DeleteStatement \
     include/de/DictionaryExpression \
     include/de/Evaluator \
     include/de/Expression \
@@ -41,6 +42,7 @@ HEADERS += \
     include/de/scriptsys/compound.h \
     include/de/scriptsys/constantexpression.h \
     include/de/scriptsys/context.h \
+    include/de/scriptsys/deletestatement.h \
     include/de/scriptsys/dictionaryexpression.h \
     include/de/scriptsys/evaluator.h \
     include/de/scriptsys/expression.h \
@@ -76,6 +78,7 @@ SOURCES += \
     src/scriptsys/compound.cpp \
     src/scriptsys/constantexpression.cpp \
     src/scriptsys/context.cpp \
+    src/scriptsys/deletestatement.cpp \
     src/scriptsys/dictionaryexpression.cpp \
     src/scriptsys/evaluator.cpp \
     src/scriptsys/expression.cpp \